http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48249
Summary: gcc-4.6: __builtin___memmove_chk wrong results
Product: gcc
Version: 4.6.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: regression
AssignedTo: unassig...@gcc.gnu.org
ReportedBy: holger.h...@sap.com
__builtin___memmove_chk produces wrong results if src and dest are
overlapping (gcc-4.6 rev. 171299 and trunk):
this is already wrong (source mm.c):
typedef long unsigned int size_t;
extern __inline __attribute__ ((__always_inline__)) __attribute__
((__artificial__)) void *
__attribute__ ((__nothrow__)) memmove (void *__restrict __dest, __const void
*__restrict __src, size_t __len)
{
return __builtin___memmove_chk (__dest, __src, __len, __builtin_object_size
(__dest, 0));
}
void memmove2 (void *dest, const void *src, size_t n)
{
memmove (dest, src, n);
}
correct test program that triggers wrong results (source m.c):
#include <string.h>
#include <stdio.h>
void memmove2 (void *dest, const void *src, size_t n);
int main()
{
char s[50];
strcpy (s, "abcdefghijklmnop");
memmove2 (s+2, s, 14);
printf ("%s\n", s);
return 0;
}
reproduce (linux, x86_64):
$ gcc-4.6 -O2 -c mm.c -o mm46.o
$ gcc-4.5 -O2 -c mm.c -o mm45.o
gcc-4.6 is wrong:
$ gcc-4.6 m.c mm46.o && ./a.out
abababefefijklmn
gcc-4.5 produces correct result:
$ gcc-4.6 m.c mm45.o && ./a.out
ababcdefghijklmn
